This is a pressing question for pastors today. Ultimately, there is only one thing to preach: the Word of God. We certainly cannot preach our own hobby-horses. We cannot preach anything but Christ crucified and raised from the dead. We cannot preach a health and wealth “gospel.” We cannot preach the newest fad. We preach the unchanging Word to a changing world, to use Harvey Conn’s helpful book title.
However, there is greater specificity needed here. How do I preach the Word? What part of it should I preach? The answer to the first question is that expository preaching is the best form of preaching. Every example of preaching in the Bible is expository preaching. You take a portion of Scripture, explain it by showing Christ in it, and apply it to people’s lives. Furthermore, I believe the most logical way to preach expository sermons is to preach consecutively through a book of the Bible. I do not believe that it is wise to preach Genesis, then Exodus, then Leviticus. People need a balanced diet of the various genres of Scripture. They need narrative, poetry, gospel, apocalyptic, prophetic, proverbial, and epistolary. They need a healthy balance of Old Testament and New Testament.
Knowledge of the congregation’s struggles is probably the key element in deciding which book of the Bible the people need next. If they don’t know what the good news is, then preach John or Romans. If the congregation has significant unity issues, preach Ephesians. If the people need wisdom because of stupid decisions they are making, preach Proverbs. If the people are to wrapped up in the here and now, preach apocalyptic (Daniel or Revelation). If the people are too legalistic, preach Galatians. If the people are to antinomian, preach James, Exodus, or Deuteronomy.
Lastly, within the parameters of what the people need, there is usually more than one book from which to choose, and more than one need of the congregation. Ultimately, of course, every congregation needs the whole Word, even if some needs might be sharper than others. So, how to decide among these various needs? I decide very simply by which book has the best number of solid commentaries on it. For instance, Acts is completely off the radar screen for at least ten years, since it is so woefully served by commentaries, and there are so many good ones coming out in the next ten years. By the way, to know what is coming out, this page is undoubtedly the most complete and up to date (Jeremy keeps it very up to date constantly). Exodus, on the other hand, is now served by an embarassment of riches in Cassuto, Childs, Currid, Enns, Houtman, Mackay, Motyer, Propp, Ryken, and Stuart, not even including many lesser but still helpful lights in Brueggemann, Fretheim, and Kaiser. Furthermore, Matthew Poole’s Synopsis is now half available (with the rest to follow shortly). With that and the Ancient Christian Commentary, and Keil/Delitzsch, you have a fairly complete access to all the best comments in the ages of the church, and with Carasik, you have the best of Jewish thought on the book. So, Exodus makes sense for me after I finish 1 Peter (which is another book now served with an embarassment of riches).